With the rapid development of display technology, touch screen panels have become popular in people's life. At present, touch panels can be classified according to their constitution structures into add-on mode touch panels, on-cell touch panels and in-cell touch panels. For an add-on mode touch panel, the touch panel and the liquid crystal display (LCD) are produced separately and then attached together to form a liquid crystal display with touch function. For an on-cell touch panel, a touch component is directly manufactured on a side of the color filter substrate of the liquid crystal display opposite to the liquid crystal layer. With respect to the add-on mode touch panel, the on-cell touch panel can reduce the thickness of the entire touch panel and increase light transmission rate.
Generally, the touch component in an on-cell touch panel consists of a plurality of touch detection points arranged in a matrix. In performing a touch operation, the touch driving circuit in the touch panel will charge and scan, namely load scanning signals to, these touch detection points line by line, and acquire touch signals from respective touch detection points in sequence; the touch driving circuit determines whether the touch detection points are touch points by comparing magnitudes of touch signals with a touch threshold value; and the touch driving circuit reports to the system for conducting a corresponding operation after determining the touch point(s).
While the touch driving circuit is detecting touch, the display driving circuit in the touch panel drives the display panel to display normally. In general, the refresh frequency for the display driving circuit in the touch panel is generally about 60 Hz, and the refresh frequency for the touch driving circuit is generally about 90 Hz, thus they are different frequencies. Noise will be generated during the refreshing operation of the display driving circuit, and the noise has a frequency consistent with the refresh frequency. The noise would interfere with the touch signals acquired by the touch driving circuit, reduce signal-to-noise ratio of the touch signals, hence influencing accuracy of the touch determining operation by the touch driving circuit.